Bulb changer



April 8, 1952 J. A. MCDERMQTT BULB CHANGER Filed Jan. 16, 1950 I VE TOR.

JUUIYW A. M: ozkmm S; ATTORNEY.

Patented Apr. 8, 1952 UNITED STATES PATENT OFFICE BULB CHANGER Julian A.McDermott, Elmhurst, N. Y.

Application January 16, 1950, Serial No. 138,837

2 Claims.

This invention relates to means to increase the reliability of signallights which are operated on a repeating cycle.

The invention has reference to devices which employ a condenserdischarge as an inherent timing medium, as well as a source of power foroperating either an incandescent or a gaseous discharge lamp.

An illustration of the kind of device herein referred to may be found inU. S. Patent No. 2,221,867 owned by the present applicant, wherein alamp is continuously flashed by the repeated charging and discharging ofa condenser. With this arrangement, a relay holds a lamp circuit openuntil the condenser reaches a predetermined condition of charge. Thedecrease in the charging current causes the relay to release thearmature, closing the circuit through the lamp. The condenser dischargesand the cycle repeats, resulting in continuous flashing of the lamp.However, one difliiculty with this arrangement is that here, as in allelectrical lamps, the possibiilty of a bulb burn-out exists.

It is therefor the principal object of the present invention to reducethe probability of the failure of electrical equipment due to theburnout of bulbs or gaseous discharge tubes.

It is another purpose of the present invention to provide suchelectrical equipment with means for automatically substituting a reservebulb or tube Whenever a bulb or tube in the equipment is burned out.

And still another aim of the present invention resides in the provisionof a plurality of reserve bulbs so that the equipment will continue tofunction even in the event that more than one bulb or tube burns out.

There and other meritorious aims and advantages, which will become morefully apparent as the description hereof proceeds, are attained by thenovel combination and arangement of parts, hereinafter described, andillustrated in the accompanying drawing, forming a material component ofthis disclosure, and in which:

Figure l is a schematic view of a circuit, showing the bulb changer ofthe present invention.

Figure 2 is a modified form of bulb changing means.

Figure 3 is still another modification of a circuit including the bulbchanging device of the present invention.

Figure l is yet another modified circuit and bulb changing device.

Figure is a still further modification of an electrical circuit and bulbchanging device; and

Referring in greater detail to the drawing, and specifically to Figure 1thereof, in the circuit illustrated, numeral II is the main relay coil,

numeral [2 illustrates the first lamp to be used;

I3 is the armature of the main relay, I4 is the condenser to be charged,is a. source of power more relays in series.

2 such as a battery, I6 is the coil of a second relay, and i1 is anarmature controlled by the second relay coil.

When a source of power, such as battery l5 here illustrated, isconnected into the circuit, a current rushes'through the relay coil I I,and the coil [6 of the second relay. Current through these relay coilseffects the movement of armatures l3 and 11, so that they move in opencircuit positions with respect to bulb l2 and reserve bulb l8. Ascondenser I4 reaches a charged condition, the current value decreases,and as a result thereof, relay H, being the less sensitive as far ashold in value is concerned, releases its armature I3 to close a circuitfrom condenser 14 through lamp I2. Condenser M then discharges, flashingthe lamp [2,

The inrush of current which results due to the tendency to rechargecondenser l4, operates the armature l3 and the circuit through lamp I2is again opened. This cycle is repeated as the condenser charges anddischarges.

If however lamp [2 burns out, the cycle will change in this manner: Thedecrease of current as the condenser becomes charged, causes armature 13to operate as hereabove described. If the lamp l2 burned out, thecondenser 14 will not discharge, and the current will continue todecrease. When it has decreased sufliciently, armature l1 operated bythe second relay coil [6, the said relay being more sensitive than relayII, will drop out, closing the circuit through lamp [8. This cycle willrepeat each time the condenser becomes charged, and the bulb l8 willflash. Replacement of the burned-out bulb I2 will cause the device toflash normally again.

Figure 2 shows an arrangement similar to that illustrated in Figure 1,except that the relay coils in Figure 2 are placed in series. In Figure2, numeral I2 is the main relay coil, 22 shows the first lamp to beused, 23 is the armature of the main relay, 24 is the condenser to becharged, 25 is the source of power such as a battery, 26 is the coil ofthe second relay, 2'! is the armature controlled by said second relaycoil and 28 is a reserve bulb.

The resistance 24 could be used to vary the voltage across the thermalswitch and hence control heat-up time. The rate and balance could alsobe effected by a second winding.

It may thus be seen that any number of relays may be used to control anyequivalent number of bulbs. Hence the circuit shown in Figure 1 couldhave two or more relays in parallel, and the circuit shown in Figure 2could have two or It is also possible and at times it may be desirableto put two relay coils in parallel and one or more relay coils inseries. Replacement of the burned out bulb 22 will start the deviceflashing normally again, as is hereabove described.

The basic principle here involved is the use of relay means controlledby the condition of charge on the time and/or power condenser to switchin reserve lamps.

Figure 3 shows another variation of the same idea. It is well known thatthe method of replacing bulbs at an optical center is the use of amechanical bulb changing device. One such device is shown in Figure 3employing the arrangement outlined in connection with Figures 1 and 2.In this arrangement, the second and most sensitive relay operates amotor, spring, solenoid or any other suitable and desirable mechanicalmeans so that a series of bulbs may be successively substituted asburn-outs occur.

In'Figure 3, 3| is the main relay coil, 33 is the corresponding bulbflashing armature, 32 is the first lamp to be used, 34 is the condenserto be charged, 35 is a source of power such as a battery, 36 is the coilof a second relay, 31 is an armature controlled by relay coil 36, 39 and40 indicate reserve bulbs, ill is an electro-mechanical escapement latchand 43 is the holding element.

This device operates as follows: Under normal conditions, the decreaseof the charging current causes armature 33 to drop out because the relaywith armature 32 is the least sensitive, flashing bulb 32 as in thecircuits shown in Figures 1 and 2. However, if the connected lamp 32fails, the current through the relay coil continues to decrease andarmature 3! drops out. Movement of armature 3'1 closes a circuit throughan electromechanical escapement latch such as 4|, resulting in movementof element 43 holding replacement bulbs. A new bulb 35 drops into place,and the condenser is discharged, thus causing the repetitive flashing ofthe bulb.

If the optical position of the lamp is not important, a multiplicity oflamps may be connected in succession. This arrangement is shown inFigure 4, wherein numeral indicates the main relay coil, 52 indicates aplurality of bulbs, 53 is the armature of relay coil 5|, numeral 54represents the condenser to be charged, 55 is a source of power such asa battery, 56 is the coil of a second relay, and 51 represents anarmature controlled by it.

In operation, when the double pole switch 64 is closed, the rush ofcurrent into the condenser 54 energizes the coils of relays 5! and 56,which operate their respective armatures 53 and 57, opening theircircuits. As the condenser becomes charged, the current decreases and,since relay coil 51 is the sensitive, armature 53 drops out, closing itscircuit, permitting the discharge of condenser 53 through bulb 52. As inthe previous disclosures, the operation is repetitive. Should howeverthe bulb burn out, the charging current into the condenser will continueto decrease until the relay 56, which is the most sensitive, has itsarmature 51 drop out, closing on a circuit through auxiliary battery 56.The resulting current operates a rotary magnetic switch having coils 61and an armature 68, so that reserve bulb 52 would be connected acrosscondenser 54. The discharge of condenser 54 causes the energizing ofcoils 5| and 56 and the repetition of the normal flashing cycle.

The principles shown are not limited to the particular form of circuithereabove illustrated. Whenever the charging and discharging of acondenser is used to flash a lamp, the principle herein described isapplied, namely the condition of the condenser current and/or voltagebeing the controlling factor in the timing cycle. Whenever the cyclebecomes longer than normal, due to bulb failure, or the failure of anyother operating device to discharge the condenser, the operation of asecond relay of different selectivity permits automatic substitution forthe defective element. Thus in Figure 5 the numeral BI is the coil of arelay, the armature of which is shown at 61. When battery 65 isconnected, current rushes into condenser 64 energizing coil 6| to openthe lamp circuit 62 by movement of armature 61. The flasher operation iscyclic as hereabove described so that, if bulb 62 burns out, armature 61closes the lamp circuit, but con- .denser 64 does not discharge. Thecondenser voltage continues to rise and when it reaches a predeterminedvalue, it actuates relay coil 68, moving armature 63 to close a circuitthrough a bulb changing mechanism 60 either of the type previouslydescribed, or of any other suitable and desirable nature. A gaseousdischarge tube 63 the purpose of which it is to break down at apredetermined voltage, may be added to prevent loss of power duringnormal operation.

Thus there has been illustrated and described a bulb replacingarrangement in the principal form of its embodiment and in severalmodifications. It is to be understood that this disclosure is to beregarded as illustrative and descriptive only of the best known forms ofthe present invention, and not as limitative or restrictive to the exactdetails shown, applicant reserving the right to make such changes andalterations in the construction as may come within the scope of theappended claims without thereby departing from the spirit or the scopeof the present invention.

Having thus described the invention, what is claimed as new and desiredto secure by Letters Patent, is:

1. In a bulb changing device to be used in connection with a lampflashing circuit, relay means to successively switch in reserve bulbs asbulbs are burned out, said circuit including a con denser and means forcharging it during the lamp off of the flashing cycle and discharging iton each flash, said relay means controllable by the current into saidcondenser, said relay operable when the charging current into saidcondenser drops below the minimum established by the normal time ofrepetition of the flash and the simultaneous discharg of the condenser.

2. In a bulb changing mechanism associated with a lamp flashing circuit,relay means to successively switch in reserve bulbs when the operatingbulb burns out, said circuit including a condenser and means forcharging said condenser during the lamp 01f part of the flasher cycleand discharging it on each flash, said relay means controllable by thevoltage across said condenser, said circuit bein so selective as tooperate when the condenser voltage increases above the maximumestablished by the normal time of repetition of the flash and thesimultaneous discharge of said condenser.

JULIAN A. MCDERJMOTT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,918,480 Moore July 18, 19332,168,785 Agnew Aug. 8, 1939 2,221,867 Feingold Nov. 19, 1940

